Mike Dilger’s wildlife spectacles
The broadcaster, naturalist and tour guide shares the most breathtaking seasonal events in Britain
Free Fallin’
HUNTING PEREGRINES
Spot the ultimate urban predator ‘stooping’ to catch prey this summer
FEW, IF ANY, BIRDS ARE CAPABLE OF commanding a fraction of the respect and awe bestowed upon Britain’s largest falcon. Recovering from a low in the 1960s, when only 385 pairs were recorded, the recent upturn in the peregrine’s fortunes to reach about 1,750 pairs is one glimmer of hope amongst a veritable tsunami of species declines recorded elsewhere.
Justifiably deserving its title of ‘fastest bird on Earth’, the peregrine falcon is also the world’s most cosmopolitan bird of prey. Comprising at least 17 different recorded subspecies, peregrines can be found breeding on every continent bar Antarctica.
In Britain, peregrines were traditionally confined to craggy locations or coastal areas, primarily in the north and west. However, having reinvented themselves as the ultimate urban predator, an increasing number are now nesting in towns and cities, where power stations, pylons, high-rise tower blocks and cathedrals offer the perfect replicas of this species’ ancestral cliff-ledge home.
“The peregrine falcon is the fastest bird on Earth and the world’s most cosmopolitan bird of prey”
Like many birds of prey, the female or ‘falcon’ is about a third larger than the male or ‘tiercel’, but both sexes have the same blue-back upperparts and streaked underparts, while a black hood and ‘moustache’ contrast with their white cheeks and throat. Courtship flights and mating take place in March and clutches are laid a few weeks later before hatching after a month-long incubation. By early June the brood are well-feathered and have an insatiable appetite; parents need to put in long hunting shifts if they are to keep up with the incessant demands of their young family.
Peregrines feed almost exclusively on small to medium-sized birds. They will also frequently focus on what may be locally most abundant – such as golden plover and red grouse in the uplands, and seabirds on the coast, while feral pigeons and starlings make popular meals in urban areas. However, studies of plucked feathers and grisly prey remains have revealed peregrines are also supremely opportunistic – an Arctic tern was recorded at a nest site in Derby, while corncrake was found to be on the menu for a pair breeding in Bath.
“Corncrake was found to be on the menu for a pair breeding in Bath”
While peregrines have been observed catching their prey directly from its perch, or by flushing any concealed birds through repeated low flights over vegetation, the most commonly recorded hunting technique is the ‘stoop’. The peregrine folds in its wings and tail, becoming the shape of a tear drop. Then it plummets downwards at an immense speed and a fairly steep angle, before employing its talons to strike its victim in mid-air. Often the target will be killed immediately on impact, but if it is still alive and kicking, it will be quickly dispatched using a special notch on the peregrine’s upper bill – the tomial tooth – that breaks the prey’s neck and spinal cord.
There seems little doubt that peregrines are capable of reaching 290kph, with research indicating their flight path is curved. This enables them to hold their head straight, thereby reducing aerodynamic drag, while also keeping their prey at the best angle for maximum visual acuity.
To avoid lung damage from the pressure changes that accompany diving at such high speeds, peregrines also possess specialised ‘tubercles’ in their nostrils. These small, bony protuberances reduce the speed that air enters their passageways and help manage the rapid changes in air pressure – allowing the bird to breathe more easily while diving. A semi-transparent nictitating membrane also operates as an inner eyelid and is drawn over the eye to protect it from wind and dust at top speed, while still allowing the peregrine to ensure an accurate strike of their prey. So successful is this hunting technique that peregrine expert Ed Drewitt says up to a third or more hunts by a breeding pair will end in a successful kill.
With the young ever more boisterous and keen to take to the air themselves during this busy month, why not use your lunch hour to find a vantage point, before enjoying some free, high-octane entertainment?
Did you know?
Under Schedule 1 of the Wildlife and Countryside Act 1981, it is an offence to intentionally take, injure or kill a peregrine falcon
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Fluttering feathers
When plucking their victims on highup perches, the preys’ feathers tend to rain down onto the streets below. When collected and identified, over 100 different birds have been recorded, revealing the peregrines’ diverse prey range, which includes kingfisher, teal and snipe.
Noisy Neighbours
As the nest activity intensifies, peregrines can become incredibly vocal. Perhaps the most distinct calls are a variety of shrill ‘kek’ sounds – often repeated in quick succession – with the smaller male’s calls being higher pitched and less raucous than that of his mate.
TV stars
A number of urban peregrine nests now have livestreams, enabling you to see the comings and goings of adults, and the development of youngsters. Livestreams of all the action from Chichester, Sheffield and Leamington Spa, to name but a few places, can be easily found online.
NEXT MONTH
Mike shares his tips on where to see machair in bloom